Orthotic devices and appliances commonly referred to as “orthotics,” have been utilized for many years by orthotists, physical therapists, and occupational therapists to assist in the rehabilitation of patient's joints and associated limbs or adjacent skeletal parts of the patient's body.
Webster's New College Dictionary defines “orthotics” as a branch of mechanical and medical science that deals with the support and bracing of weak or ineffective joints or muscles.
Orthotics or limb braces have been designed to support and protect the joint, alleviate pain associated with joint movement, and to rehabilitate the joint over time with orthotic use.
Primary osteoarthritis is usually related to aging. With aging, the water content of the cartilage increases and the protein makeup of the cartilage degenerates. Repetitive use of the joints over the years can irritate and inflame the cartilage, causing joint pain and swelling. Eventually, cartilage begins to degenerate by flaking or forming tiny crevasses. In advanced cases, there is a total loss of cartilage cushion between the femur and tibia bones at the knee joint, leading to diminished joint space on the affected side of the knee resulting in pain and limitation of joint mobility. Inflammation of the cartilage also can stimulate new bone outgrowths (spurs) to form around the joints causing increased pain and joint inflammation.
Osteoarthritis is often described as “wear and tear” arthritis, as it is highly correlated to age. Osteoarthritis is one of the most frequent causes of physical disability among adults. More than 20 million people in the US have the disease. By 2030, 20 percent of Americans, about 70 million people, will have passed their 65th birthday and will be at risk for osteoarthritis.
Osteoarthrosis is a condition where the joint is affected by degeneration. Osteoarthritis implies the same meaning, but the “it is” adds the meaning that the joint is inflamed. The two terms are often used interchangeably.
Joint replacement surgery of the knee is the surgical treatment for osteoarthrosis or osteoarthritis. It is best to delay knee joint replacement surgery as long as possible, as a total knee replacement may need to be replaced in ten to twenty years. It is a major surgery which requires considerable rehabilitation therapy to restore full function.
Exercise, weight loss if needed, and the use of anti-inflammatory medications and analgesics are often prescribed to assist the patient in managing the pain associated with osteoarthritis. Minimizing the progression of the damage to the cartilage of the knee joint and preventing the formation of bone spurs from “bone on bone” during knee joint bending is an important part of patient care.
The actual pain of osteoarthritis or osteoarthrosis comes from wearing away of the soft cartilage that pads the junction of the femur (upper leg bone of the knee) and the tibia (lower leg bone of the knee). With irritation of the joint, bone spurs can form causing bits of bone and cartilage to break off which float inside the joint space further irritating the knee. The most common form of osteoarthritis or osteoarthrosis is unicompartmental, meaning that only one of the three compartments of the knee joint are significantly affected by the loss of cartilage padding. The medial compartment of the knee is on the inside of the center line of the body. The lateral compartment of the knee is on the outside plane of the body, and the patellar compartment is in the center top of the knee behind the patella or knee cap. The majority of cases of osteoarthritis are medial compartment degeneration where the cartilage or cushioning of the knee joint has significantly deteriorated. The knee then becomes imbalanced, with the knee bowing outwards. This is often called a “bowleg” condition. A “bowleg” (genu varum), commonly referred to as a varus deformity of the knee joint, places significant force on the medial compartment of the knee, which aggravates the pain associated with osteoarthritis when the patient walks, bends the knee, or stands up.
As the cartilage or padding of the knee joint on the lateral compartment cartilage is worn away, the knee will deform abnormally bending inwards at the knee joint giving the patient a knock kneed appearance. This is referred to as a valgus deformity of the knee joint.
Osteoarthritis knee braces are designed to do two things: first, correct the abnormal bending of the knee joint inwards or outwards (varus or valgus correction). Secondly, many osteoarthritis knee orthotics or braces are designed to prevent the “bone on bone” contact of the femur and tibia bones in the medial or lateral compartment of the knee joint as the patient bears weight during ambulation. This action of lifting femur, pulling down the tibia or keeping the femur and tibia bones from coming in contact during the straightening of the knee during heel strike is often called “unloading” the knee joint. By “unloading” the knee joint, the constant irritation of the degenerated cartilage in the affected compartment of the knee (medial or lateral) can lead to a significant reduction in pain and further injury to the knee joint. Osteoarthritis knee braces also provide improved alignment of the upper and lower aspects of the knee joint by preventing the bending inwards or outwards of the knee joint during gait. These two features, unloading and alignment are provided by most of the osteoarthritis knee orthotics available in today's market.
The majority of knee orthotics available to treat osteoarthritis of the knee utilizes a single upright attached to an upper thigh cuff and lower shin cuff. The upright is located on the side of the collapsed compartment of the knee; i.e. medial side for medial compartment osteoarthritis. The attached cuffs “offload” the biomechanical force on the affected compartment of the knee by increasing the joint space on the affected side as the knee goes from flexion to extension. Many osteoarthritis braces use an angled strap from the upper part of the brace that goes across the opposite side of the knee joint from the side bar or upright to improve the alignment of the knee during ambulation to better balance the forces on the knee during gait more evenly. The strap provides a three point leverage that pulls the knee joint into proper alignment during gait. A combination of the single sided upright with cuff attachments and the valgus producing strap have shown to provide improved performance in severe genu varum osteoarthritis. However, it is difficult to set the desired degrees of flexion and extension.
Although many of the existing knee braces containing locking hinge assemblies serve their intended purpose, difficulty in ease of setting the desired degrees of flexion and extension continues to be a problem. Improvement is needed whereby a swing assist mechanism is provided for any type of knee brace, either having flexion and extension degree setting points or without such setting points, but which assists the knee brace to swing outward and then return for improving knee performance and correcting abnormal gait in a patient using such knee brace.